Catch-at-age data from New Zealand fisheries
by
Brian Bull
National Institute of Water and Atmospheric Research
Coauthors: Dave Gilbert

Catch-at-age analysis estimates the age and size distributions of fish taken by a commercial fishery, based on samples of fish from individual catches. The resulting age frequencies are key inputs to the stock assessment process, which assesses the sustainability of the fishery. Catch-at-age analysis is undertaken for most major New Zealand finfish stocks, including hoki, orange roughy, and snapper.

I will talk about the sampling programme and the quirks of the resulting data. The analysis is statistically straightforward but involves several interesting issues, including the choice of stratifying variables, the bootstrapping technique used to calculate the variability of the estimate, and the two competing methods used to convert length distributions to age distributions.

Date received: July 22, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cahg-06.